CHASKA, Minn. — Three players took turns sharing the lead with Tiger Woods until he stood alone at the PGA Championship.

The final hour at Hazeltine changed everything.

Woods fired off three straight birdies, which began with a drive onto the fringe of the 299-yard 14th hole and ended with Woods nodding his head and dangling his tongue out of the side of his mouth after making a 20-footer.

He finished with a 2-under 70 to build a four-shot lead, his largest through 36 holes at a major since the 2005 British Open at St. Andrews, when he led by five.

Woods is 8-0 when leading a major through 36 holes, and his chances only improved as everyone around him faltered.

"In order to have a lead in a major championship, you can't be playing poorly," said Woods, who was at 7-under 137. "And all the times that I've been in this position, I have played well. And I'm playing well now."

Ross Fisher was the last challenger to crumble. Tied for the lead with two holes to play, he came up woefully short on the par-3 17th and hit a drive that left him an awkward stance in the sand, both shots leading to bogey and a 68. Padraig Harrington was tied with eight holes to play until he made three straight bogeys, closing with another bogey when he missed a 3 1/2-foot putt. He finished with a 73.

Before them was Graeme McDowell, who couldn't keep the ball dry and wasted a good start by shooting 75.

Fisher and Harrington finished four shots behind at 3-under 141, along with Vijay Singh (72), U.S. Open champion Lucas Glover (70) and Brendan Jones (70).

"I mean, yes, Tiger is the greatest golfer I think we've ever seen," Fisher said. "But at the end of the day, he's just like me and you. He's just a human being. He just happens to be damn good at golf."

Woods has not lost a 36-hole lead on the PGA Tour in five years, dating to the Byron Nelson when he was revamping his swing. He came to Hazeltine having won his last two tournaments, however, and appears to be hitting his stride.

Woods avoided his second bogey in three holes with a 12-foot par save at No. 12, missed a birdie opportunity to take the lead on the 13th, then poured it on. The tees on the 352-yard 14th hole were moved up, giving players the option of trying to drive the green.

Woods flushed his 3-wood onto the green and just onto the fringe, nearly holing the eagle putt. On the par-5 15th, he hit 3-wood through the green and chipped to tap-in range to widen the lead. Then came the 16th, and a putt that gave this major that inevitable feeling of Woods hoisting the Wanamaker Trophy for a record-tying fifth time.